、。
We've been married for thirty years.
Literal
We [topic-は] married-and 30 year becomes.
The pattern 結婚して[time]になる ('have been married for [time]') — te-form of 結婚する chains to になる ('becomes [time]'). Literally 'having married, 30 years become' — the 30 years have accumulated since the marriage event. A standard way to express duration since a change of state.